This invention is directed to an electrical connector and more particularly to an improved BNC type, panel mount electrical connector.
Capacitively decoupled connectors were developed several years ago as a way to reduce noise and eliminate ground loops on coaxial interconnections. The highfrequency noise generated by fast rise times can cause both false triggering of circuits as well as emissions that can be radiated or conducted outside the equipment. Such emissions can interfere with nearby equipment. Ground loops are also a problem for networked systems. Ground loops are caused when two interconnected units are at different voltage potentials.
One early approach to handling such EMI and ground loop problems was to decouple the cable shield from the ground panel by soldering a ceramic disk capacitor between the cable shield and the panel. The capacitor shunts high-frequency noise to ground. While effective, this approach is time consuming and expensive. Another approach is found in U.S. Pat. No. 4,884,982, assigned to the assignee hereof, where the teachings thereof are incorporated in this application in their entirety. The BNC type connector, as taught by the patent, has built-in chip capacitors. These capacitors establish the electrical contact between the outer shield and a clip. The clip provides a short electrical path between the capacitors and panel. As a result, high-frequency noise is effectively shunted to ground, while any DC signals are blocked.
Another feature of the patented device is the inclusion therein of a voltage discharge path between the clip and the shell of the connector. This feature, which preferably incorporates a dielectric wafer, such as glass, mica or ceramic, in the path, protects the connector and capacitors from exposure to elevated voltages.
A problem exists with this design in that there is no direct ground connection to a circuit board. The ground connection is achieved by a ground path passing through a conductive panel.